RDM and BRD have the same length of silence yes, but BRD can weave it during its burst while RDM silence shares recast with its GCDs and therefor cannot weave it while bursting.
Let's talk about NIN+BRD then.
BRD silence has a 20sec cooldown, no? Mug and Assassinate ALSO have 20sec cooldowns, so for every silence NIN can use Mug (buffing the BRDs burst ontop of it btw) and then do a 19.8k Assassinate (13.2k+6.6k if they have bunshin stacks active for it) into a 17.6k Hyosho in 2sec (the silence duration) adding up to 37.4k damage (39.4k I guess if you really wanna count Mug's 2k LOL) from just the NIN using those 2 alone, not counting the BRD's burst which would add the total damage up much further. If you try to do this same thing with RDM silence, it won't have the same effect because RDM can't just weave its silence between GCDs, Resolution shares recast with its GCDs.
In CC, having even 1 extra number of advantage matters a lot (unless your teams just that bad), so BRD being able to setup KOs like it can makes it very useful, because if that KO setup works then you immediately just took out a number from the enemy side and likely gain numbers advantage because of it. Similarly to MNK LB in a way, except MNK LB being uncleansable and MNK can solo KO people if it wants to, or just use its LB as CC to setup a quick KO for their team; however BRD can silence every 20sec while MNK can only LB every 75sec (not counting if it gains gauge from BRD LB or map things like the coins on Clocktown or feathers on C9/btw don't play MNK on C9 pls it's very bad for you), Purify being 30sec CD with 5sec immunity when used means BRD gets a full 25sec window to use silence on the people who use Purify, setting up KOs for their team. That is why BRD is valuable, and maths aren't going to arrive you to that conclusion because it's a situational kit advantage.
Speaking of MNK btw, I don't know if you slapped its moves next to eachother just for numbers case and didn't care about the correct order, because the combo you listed in the googledoc anyone can just prevent from being done.
There's many different orders of MNK LB combo or burst combos, and that one ain't it.